1. Field of the Invention
The present invention relates to an air conditioning system for vehicles, and, more specifically, to an air conditioning system suitable as an air conditioner for a cabin of a work vehicle.
2. Description of the Related Art
In work vehicles, such as power shovels, generally an air conditioner is provided for conditioning air in a cabin. In the vehicle, a door or a window of a cabin, or both, may be opened during vehicle operations. In such conditions, the load for cooling may increase such that it is difficult to achieve a degree of air conditioning comfortable to an operator. For example, when a door or a window is opened in warm weather, the temperature or amount of air blown from an air conditioner is controlled, so that the temperature in a cabin approaches a set temperature. It may be difficult to achieve a comfortable cooling condition by control by such a manner of control and by maintaining a condition in which ports continue to blow out temperature conditioned air as they are. In such a condition, the cooling effect of most of temperature conditioned air may be wasted. Moreover, a heavy load may be applied to a compressor for refrigerant provided in a cooling circuit of the air conditioner, or to a blower for sending air to be conditioned. Therefore, wasted power increases and the operation life of the equipment is reduced. Further, because the compressor usually is driven by utilizing the power of an vehicle engine, the load on the engine increases, and overheating may occur.